In the Linux kernel, the following vulnerability has been resolved:
ext2/dax: Fix ext2_setsize when len is page aligned
PAGE_ALIGN(x) macro gives the next highest value which is multiple of pagesize. But if x is already page aligned then it simply returns x. So, if x passed is 0 in dax_zero_range() function, that means the length gets passed as 0 to ->iomap_begin().
In ext2 it then calls ext2_get_blocks -> max_blocks as 0 and hits bug_on here in ext2_get_blocks(). BUG_ON(maxblocks == 0);
Instead we should be calling dax_truncate_page() here which takes care of it. i.e. it only calls dax_zero_range if the offset is not page/block aligned.
This can be easily triggered with following on fsdax mounted pmem device.
dd if=/dev/zero of=file count=1 bs=512 truncate -s 0 file
[79.525838] EXT2-fs (pmem0): DAX enabled. Warning: EXPERIMENTAL, use at your own risk [79.529376] ext2 filesystem being mounted at /mnt1/test supports timestamps until 2038 (0x7fffffff) [93.793207] ------------[ cut here ]------------ [93.795102] kernel BUG at fs/ext2/inode.c:637! [93.796904] invalid opcode: 0000 [#1] PREEMPT SMP PTI [93.798659] CPU: 0 PID: 1192 Comm: truncate Not tainted 6.3.0-rc2-xfstests-00056-g131086faa369 #139 [93.806459] RIP: 0010:ext2_get_blocks.constprop.0+0x524/0x610 <...> [93.835298] Call Trace: [93.836253] <TASK> [93.837103] ? lock_acquire+0xf8/0x110 [93.838479] ? d_lookup+0x69/0xd0 [93.839779] ext2_iomap_begin+0xa7/0x1c0 [93.841154] iomap_iter+0xc7/0x150 [93.842425] dax_zero_range+0x6e/0xa0 [93.843813] ext2_setsize+0x176/0x1b0 [93.845164] ext2_setattr+0x151/0x200 [93.846467] notify_change+0x341/0x4e0 [93.847805] ? lock_acquire+0xf8/0x110 [93.849143] ? do_truncate+0x74/0xe0 [93.850452] ? do_truncate+0x84/0xe0 [93.851739] do_truncate+0x84/0xe0 [93.852974] do_sys_ftruncate+0x2b4/0x2f0 [93.854404] do_syscall_64+0x3f/0x90 [93.855789] entry_SYSCALL_64_after_hwframe+0x72/0xdc
CVSS Details
- CVSS 3.1 Base Score: 5.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux_2023 | — | Upgrade kernel-tools-debuginfoUpgrade perf-debuginfoUpgrade bpftool-debuginfoUpgrade kernel-toolsUpgrade kernel-debuginfoUpgrade perfUpgrade kernel-debuginfo-common-aarch64Upgrade kernel-headersUpgrade kernel-develUpgrade kernel-libbpfUpgrade kernel-livepatch-6.1.41-63.109Upgrade kernel-debuginfo-common-x86_64Upgrade bpftoolUpgrade kernel-libbpf-develUpgrade kernelUpgrade kernel-libbpf-staticUpgrade python3-perfUpgrade python3-perf-debuginfoUpgrade kernel-tools-devel | Sep 30, 2025 | Sep 16, 2025 |
| Debian | — | Upgrade linux | Sep 18, 2025 | Sep 18, 2025 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Sep 16, 2025 |
Prioritise with Active Threat Intelligence
With curated Threat Intelligence, you can see which vulnerabilities truly put you at risk, prioritize what matters most, and act before attackers do.
Explore Intelligence Hub